Trim off the root end and dark green tops if desired
Slice the leek lengthwise from top to bottom
Rinse under cold running water, separating the layers to remove dirt
Soak the sliced leek in a bowl of cold water to loosen grit
Swish the leek pieces in the water
Lift the leeks out of the water, leaving the dirt behind
Repeat with fresh water if needed
Drain well before using